User manual

MRD 3187B User Manual
Page 117
It is intended to provide a similar audio level as a broadcast TV station signal through an RF
modulator. The down mix includes the “center” and “surround” channels if they are present,
and is represented as Lt/Rt. (left total/right total)
The second mode is “Monitor.” It has moderate processing, no gain boost and its down mix
involves left and right channels only (L/R). The compression setting is “Line” mode as the
default, but may be changed to “RF”, “Custom 0” or “Custom 1.” In “Line” mode, the Dolby
dialog normalization data is followed. No other parameters may set by the customer. It is
intended for monitoring of sources with only some peak limiting protection. Selecting “RF”
as the compression setting will add 11 dB of gain and the same processing as the
“Transmission” mode to the analog outputs, AES digital outputs set to PCM, and any
embedded outputs set to PCM. The down mix is L/R (left only/right only)
The third mode available is “User.” It allows all parameters to be set by the operator. The
compression choices are “RF”, “Line Mode”, “Custom 0”, and “Custom 1.” RF and “Line
Mode” essentially duplicate the first two modes of audio down mix described above. The
“Custom 0” and “Custom 1” modes have no audio processing or gain boost. “Custom 1”
does enable gain changes called for by the dialog normalization data. It allows the operator
to enable or disable the dynamic range (peak limiting) and select the channels to down mix
“Lt/Rt”, “L/R”, “Mono L”, and “Mono R”. Mono left or Mono right applies that signal to
both left and right channels of the digital service, left and right channels of the analog
outputs, and left and right channels of any embedded stream set to PCM. “Custom 0”
disregards the Dolby dialog normalization data and runs at a fixed gain. Choosing “RF” as
the compression mode will increase the gain by 11dB for the analog outputs, AES digital
outputs set to PCM, and any embedded outputs set to PCM.
If you want to run with no processing, then set “User / Custom 1 / L/R / Disabled.” This will
still allow gain changes called for in the Dolby metadata.
Audio Output Settings
The digital audio services may be set to “PCM” (AES) or “Raw” as an output. This applies
to all available sources. The “PCM” setting will pass an AES stream, or automatically down
mix an AC-3 Dolby stream to two channels. “Raw” simply passes thru the Dolby AC-3 data
stream to be decoded by an external decoder such as the Dolby 569. The analog channels
can be assigned to any of the digital services. The analog gain may be adjusted for the
desired level. The gain setting does not affect the level of either the embedded audio or the
digital services. A setting of 7 provides an output of approximately 0dBu for a digital signal
level of -20 dBFS. To check the audio output level, set “User / Custom1 / L/R / Disabled.”
This will remove any signal processing in the down mix. Set the digital service to be
measured to “PCM.” A test stream of -20dBFS will output from the digital services as -
20dBFS. If the analog channels are set to a gain setting of 7, the output should be -0.7 dBu
plus or minus 0.5 dBu. Each gain number increments or decrements approximately 2.5 dBu
per step. When you are setting the output levels it is suggested that an AC-3 stereo tone (2.0)
be used as the source. Do not use a Dolby AC-3 5.1 tone source as your test signal. The five
channels of equal tones will down mix such that one channel will be more than twenty dB
greater than the other.